Abstract: This invention includes the conception of T-independent conjugate-vaccines and its application in the induction of antigen specific IgA response. We demonstrated that 1) &agr;(1,6)dextran can elicit a markedly enhanced IgA response in T-cell free mice (20-50 fold higher than in normal mice); 2)co-injection of the molecule with other antigens can enhance the IgA response to the co-antigen; and 3)a dextran-Gag conjugate can elicit the Gag-specific IgA. Thus, the invention identified &agr;(1,6)dextran as a carrier molecule for producing the T-independent conjugates and as an adjuvant for the enhancement of IgA production. The T-independent property of these conjugates makes it especially useful in vaccinations against HIV and other infectious and non-infectious diseases associated with T-cell deficiency.